I think they hate them because there isnt much combined arms there either. When you get a plane there is little cooperation between the ground and air especially when the aircraft are just slammed into a target for a kill (unless they changed that by now). Renegade did it despite the weird balance between cost/effectiveness and individual tanks and infantry. Infantry on most maps had sections that were pure infantry but most of these routes would intersect with the vehicle section somewhere. You also had the ability to cut off vehicles or advanced infantry by destroying the relevant building, which would ineviteably hamstring the opponent as you simply needed both to succeed. There was always an option to still succeed without them, but it was hard. And that is key. Infantry and vehicles relied on each other in that game. Having advanced infantry run along with the tanks increased your chances of success enormously, and many tactics relied on tanks and infantry working together, sometimed in setups resembling mechanized infantry, to succeed. You should try out Renegade X its fan made remake on the Unreal engine for a taste of what combined arms can be.